Amplifier



FIG. 1 is a front view of an amplifier;

FIG. 2 is a rear view thereof;

FIG. 3 is a left-side view thereof;

FIG. 4 is a right-side view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a perspective view thereof. 

The ornamental design for an amplifier, as shown and described. 